The present invention concerns a gas injection device for injecting an expulsion gas into a tank for a liquid. The invention further concerns a tank for a cryogenic or storable fuel and a spacecraft comprising a tank.
At low or even zero gravity, liquids such as cryogenic fuels or storable fuels (i.e., fuels being storable for several years at room temperature) of a spacecraft and/or oxidators may be extracted from a tank by supplying pressurized inert gas such as helium or nitrogen into the tank, which then expulses the respective liquid. To maintain the functionality of the upstream equipment (e.g., of valves) of the gas supply line, a counter current of the liquid into the line, which may occur when the gas injection is interrupted, is to be obviated. Such counter current may, in particular, result from an acceleration of the tank carrying apparatus, which may be a spacecraft, for instance.
Different apparatus for separating a gas and a liquid are known. For instance, document U.S. Pat. No. 4,027,494 A discloses a phase separator involving superconducting magnets. From U.S. Pat. No. 4,848,987 A, a phase separator deploying pumps and valves is known. Document U.S. Pat. No. 7,077,885 B2 discloses a phase separator including a propeller and a membrane.
Due to the respective specific components, these devices are often fragile and laborious in the production.
Moreover, separator devices known from documents U.S. Pat. Nos. 4,435,196 A and 4,617,031 A are limited to operation under gravity conditions.
Document DE 10 2008 026 320 discloses a device preventing intrusion of a liquid into a gas line, wherein a separation of gas and liquid is achieved by means of meshes including a gas bubble. However, the device being applicable not only when a gas supply into the tank is stopped, but also when gas is discharged from the tank, is rather complex and, therefore, costly in production.